| 摘要 |
PURPOSE:To obtain a beam splitter which has substantially no absorption loss, is small in the difference of reflectivity or transmittance between S polarized light and P polarized light and has excellent durability by adequately determining the film thicknesses of respective layers of alternate layers consisting of TiO2 and SiO2. CONSTITUTION:The multi-layered dielectric films C formed on the surface of a substrate B are made into the 6-layered structure formed with the 1st layer 1-6th layer 6 successively from the substrate B side to the air A side. The 1st layer 1, the 3rd layer 3 and the 5th layer 5 are thin high-refractive index films consisting of TiO2. The 2nd layer 2, the 4th layer 4 and the 6th layer 6 are this low-refractive index films consisting of SiO2. The optical film thicknesses of the respective layers are lambda0/r, lambda0/2, lambda0/2, lambda0/4, lambda0/4, lambda0/2 successively from the 1st layer. lambda0 is a design wavelength and is adequately set according to the wavelength of a light source to be used. The absorption loss is thereby substantially eliminated and the difference of the reflectivity or transmittance between the S polarized light and the P polarized light is decreased. |
